Safety mechanism for automobile lifts

ABSTRACT

A rod is mounted to move with the piston or plunger of the lift. This rod is slabbed off at diametrally opposite sides; and it is reciprocable in the bore of a collar fixed in the floor of a garage. The collar has two balls in it which ride in diametrally opposite grooves in the collar, that have downwardly converging outer surfaces. Normally the balls ride on diametrally arcuate cylindrical surfaces of the rod to lock the rod in any elevated position. When the rod is rotated, however, to bring the slabbed off portions of the rod into engagement with the balls, the rod is released. The rack and the automobile thereon may be lowered to floor level. A handle is provided to rotate the rod. When the handle is released a coil spring returns the rod automatically to locking position; and the lift is locked in any position to which it has been raised. The only manual motion required of this device is to unlock it. The lock remains unlocked as the lift is lowered.

United States Patent [191 MacPherson [451 Sept. 3, 1974 1 SAFETY MECHANISM FOR AUTOMOBILE LIFTS [76] Inventor: Roger MacPherson, 148 Mibank St.,

Rochester, N.Y. 14619 [22] Filed: Apr. 9, 1973 [21]v Appl. No.: 348,882

[52] US. Cl 187/8.49, 248/411, 403/105, 403/369 [51] Int. Cl B66f 7/18 [58] Field of Search 187/849, 8.50; 222/391; 188/67; 248/160, 161, 411; 403/105, 368, 369

[56] References Cited UNITED STATES PATENTS 1,847,188 3/1932 I Kreidel 222/391 X 1,921,912 8/1933 Phillips 222/391 2,564,267 8/1951 Manke 187/849 2,670,881 3/1954 Sjiiblom 222/391 X 2,849,084 8/1958 Hott et a1 187/85 Primary Examiner-Robert B. Reeves Assistant ExaminerI-Iadd Lane 5 7 ABSTRACT A rod is mounted to move with the piston or plunger I of the lift. This rod is slabbed off at diametrally opposite sides; and it is reciprocable in the bore of a collar fixed in the floor of a garage. The collar has two balls in it which ride in diametrally opposite grooves in the collar, that have downwardly converging outer surfaces. Normally the balls ride on diametrally arcuate cylindrical surfaces of the rod to lock the rod in any elevated position. When the rod is rotated, however,

.to bring the slabbed off portions of the rod into engagement with the balls, the rod is released. The rack and the automobile thereon may be lowered to floor level. A handle is provided to rotate the rod. When the handle is released a coil spring returns the rod automatically to locking position; and the lift is locked in any position to which it has been raised. The only manual motion required of this device is to unlock it. The lock remains unlocked as the lift is lowered.

5 Claims, 9 Drawing Figures PATENTED SEP 1974 sum a'or a SAFETY MECHANISM FOR AUTOMOBILE LIFTS The present invention relates to lifting devices, and more particularly to lifting devices, such as are used for lifting automobiles to a position where they can be lubricated, or where repairs can be made thereon. In the still more specific aspect, the invention relates to a safety mechanism for holding such lifting devices in elevated position.

Many accidents have occurred, and in some instances men have been killed, because of an automobile lifting device falling while a person was working under an elevated automobile. Therefore, probably all automobile lifts made today are provided with safety mechanisms for holding the lifts in elevated positions. However, so far as the present inventor knows, all of these safety mechanisms operate only to hold the lift automatically in a fully raised position; although some can be locked manually in a half-raised position, they will not operate automatically in any position between fully lowered and fully raised position. Furthermore, even in the fully raised position, such safety mechanisms, as are known to the present inventor, leave much to be desired from a safety standpoint.

A primary object of the present invention is to provide a safety mechanism for an automobile lift, which will operate in any position, so that the automobile lift will be locked automatically in any intermediate position between fully lowered and fully raised position, and also in fully raised position.

Another object of the invention is to provide a safety mechanism of this kind which will operate automatically. V

A further object of the invention is to provide a safety lock mechanism for automobile lifts or jacks in which the lock will be effective any time the lift or jack is raised, whether the lift has been left locked or unlocked.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims particularly when read in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a fragmentary side elevation of a lifting device built according to one embodiment of this invention;

FIG. 2 is a view at right angles to FIG. 1;

FIG. 3 is a plan view of the parts'shown in FIGS. 1 and 2;

FIG. 4 is a fragmentary side elevation on an enlarged scale of the locking mechanism of this lift, shown in released position;

FIG. 5 is a similar view but with the locking mechanism shown in locking position;

FIG. 6 is a sectional view on an enlarged scale taken on the line 66 of FIG. 4;

FIG. 7 is a sectional view on an enlarged scale taken on the line 77 of FIG. 5;

FIG. 8 is a horizontal sectional view of the parts shown in FIG. 7 and illustrating the means for automatically returning the locking mechanism to locked position when the locking mechanism is released; and

FIG. 9 is a similar view but showing these parts in locked position.

Referring now to the drawings by numerals of reference, denotes the cylinder of a conventional hydraulically, or pneumatically, operated lift for lifting automobiles. Reciprocable in this cylinder is a piston (not shown), to whose upper end the superstructure 22 of the lift is secured. This may be of conventional structure. As shown it comprises the plate 24, and two spaced parallel I-beams 26 which are mounted on the plate, and the cross braces 28.

Mounted in parallelism to the cylinder 20 to move with the support 22 is a rod 30, which is reciprocable in a cylinder 32 (FIG. 2) which is embedded in the floor F of the garage in which the lift is employed. The foot 25 of the cylinder 20 is secured to this floor F.

The rod 30 is generally cylindrical, but is flatted off at two diametrically opposite points, as indicated at 34 and 36 (FIGS. 6, 7, 8 and 9).

At its upper end (FIGS. 4 and 5), the cylinder 32 is formed integral with, or has, a collar 38, secured thereto, which has two diametrically opposed grooves 40, 42 (FIGS. 6 and 7) in its bore, which have inclined, downwardly converging outer surfaces 44 and 46, respectively. Mounted to roll in these grooves are balls 48 and S0, respectively.

A handle 52 (FIGS. 4, 5, 8 and 9) is secured in the upper portion of the rod 30 to project radially therefrom. This handle is provided to rotate the rod 30. When the rod is in the angular position shown in FIGS. 4 and 8, the balls 48 and 50 ride on the flats 34 and 36 of the rod 38; and the rod can be moved readily vertically in the collar 38. When the lift is raised vertically from the position shown in FIG. 4 a sufficient distance to free the balls 40 and 50 from the flats 34, 36 and the rod is turned through ninety degrees, however, the balls 48 and 50 will engage portions 58 and 60 (FIG. 7) of the cylindrical surface of the rod, and will the lock the rod against axial movement, the arcuate surfaces 58 and 60 of the rod being further apart than the flats 34 and 36. The halls are wedged against the rod by the inclined surfaces 44 and 46 of the collar 38. Thus, the rod can be locked in any vertical position by simply rotating it ninety degrees from its released position shown in FIG. 4. Hence, with the locking mechanism of the present invention it is possible to lock the lift piston, which reciprocates in the cylinder 20 in any elevated position, since the rod 30 is secured to the plate 24 (FIGS. 1, 2 and 3) to which the upper end of the lift piston, which reciprocates in the cylinder 20, is secured.

The rod 30 is fastened to the plate 24 by a nut 62 (FIG. 2) which threads onto the upper reduced diame-,

ter portion 54 of the rod. A washer or spacer 64 may be interposed between a shoulder on the rod and the bottom face of the plate 24. I

The lift superstructure 22 is adapted to be locked in any elevated position automatically. For this purpose, a coil spring 66 (FIGS. 4, 5, 8 and 9) is provided, one end of which is engaged in a hole in the handle 52, and the opposite end of which is coiled about a pin 68 that is secured in the superstructure 22.

To adjust the lift vertically, the handle 52 is grasped and the rod 30 is rotated to its released position (FIG. 4), and air or hydraulic pressure is applied to the lift piston in cylinder 20. As soon as the lift has reached the desired height, the handle 52 is released and the spring 66 returns the rod 30 automatically to locked position 'shown in FIGS. 5 and 7, thereby automatically locking the lift itself in position.

The balls 48 and 50 are intended to move to released position by gravity; but if desired, the collar 38 may be closed at its top by a cover plate 51 and gasket 53 (FIGS. 4 and 5), and coil springs may be interposed between this cover plate and the balls to move the balls automatically to released position. Such springs, if used, will also aid the inclined surfaces 44, 46 of collar 38 in camming the balls to locking position.

The two balls doubly insure safety. If one should malfunction the other will lock the lift. Furthermore, it is never necessary to engage the locking mechanism. It is spring-loaded to engage automatically anytime the lift is raised, and in any position to which the lift is raised. The only manual motion required is to unlock the mechanism by rotating the lock bar before the lift is lowered. Any time the lift is raised, the lock is effective whether it has been left locked or unlocked.

In prior lift mechanisms when the locking device is released, the lift and its load drop a slight distance before they hit a safety stop. with the safety mechanism of the present invention, the lift is stopped automatically from dropping in case of failure of the hydraulic or pneumatic control.

While the invention has been described, then, in connection with a specific embodiment thereof, it will be understood that it is capable of further modification, and this application is intended to cover any embodiments of the invention, which fall within the disclosure or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. In a lifting device, the combination with a cylinder and a piston movably mounted in said cylinder, one of which is reciprocable vertically relative to the other, a superstructure carried by the reciprocable part for supporting the load to be lifted, and means for effecting reciprocation of the reciprocable part, of means for locking the reciprocable part in any position to which it is moved vertically comprising a vertically reciprocable rod secured to said superstructure to reciprocate therewith, a second cylinder in which said rod is reciprocable and is rotatable,

means for rotating said rod between a given angular position and a second angular position, and means for locking said rod against falling, when rotated to said given angular position, in any vertical position to which it is raised and to release said rod when rotated to said second angular position.

2. A lifting device as claimed in claim 1, having means for moving said locking means automatically to locking position when said reciprocable member has been raised to a desired vertical position.

3. A lifting device as claimed in claim 2, wherein said rod has a generally cylindrical peripheral surface, but has at least one flat surface extending along its length, and clamping means is provided at one side of said rod to engage said cylindrical surface and lock said rod against vertical movement when said rod is rotated to a position in which said cylindrical surface registers with said clamping means, and said clamping means is released when the flat surface of said rod registers therewith, and said clamping means includes a wedge surface inclined with reference to the axis of said rod, and a ball clamping member is disposed between said wedge surface and said rod to move on said rod when said flat surface registers with said member and said ball is operative, in conjunction with said surface, to lock said rod against vertical movement when said ball is in engagement with the cylindrical portion of the peripheral surface of said rod.

4. In a lifting device, the combination with a cylinder, a piston reciprocable vertically therein, a superstructure carried by said piston for supporting the load to be lifted, and means for effecting reciprocation of said piston in said cylinder, of

means for locking the piston in any position to which it is elevated comprising a reciprocable rod secured to move with said piston,

said rod having an arcuate surface around a portion of its perimeter and a plane surface extending in the direction of its axis along another part of its perimeter, a collar through the bore of which said rod is reciprocable, said collar having a groove in its bore whose outside is inclined toward said rod downwardly, a ball clamping member mounted in said groove to roll therein, and means for manually rotating said rod to move said arcuate surface or said plane surface selectively into engagement with said ball. 5. A lifting device as claimed in claim 4, wherein spring means is connected to said rod automatically to urge said rod to locked position with said arcuate surface in engagement with said ball when said manual rotating means is released. 

1. In a lifting device, the combination with a cylinder and a piston movably mounted in said cylinder, one of which is reciprocable vertically relative to the other, a superstructure carried by the reciprocable part for supporting the load to be lifted, and means for effecting reciprocation of the reciprocable part, of means for locking the reciprocable part in any position to which it is moved vertically comprising a vertically reciprocable rod secured to said superstructure to reciprocate therewith, a second cylinder in which said rod is reciprocable and is rotatable, means for rotating said rod between a given angular position and a second angular position, and means for locking said rod against falling, when rotated to said given angular position, in any vertical position to which it is raised and to release said rod when rotated to said second angular position.
 2. A lifting device as claimed in claim 1, having means for moving said locking means automatically to locking position when said reciprocable member has been raised to a desired vertical position.
 3. A lifting device as claimed in claim 2, wherein said rod has a generally cylindrical peripheral surface, but has at least one flat surface extending along its length, and clamping means is provided at one side of said rod to engage said cylindrical surface and lock said rod against vertical movement when said rod is rotated to a position in which said cylindrical surface registers with said clamping means, and said clamping means is released when the flat surface of said rod registers therewith, and said clamping means includes a wedge surface inclined with reference to the axis of said rod, and a ball clamping member is disposed between said wedge surface and said rod to move on said rod when said flat surface registers with said member and said ball is operative, in conjunction with said surface, to lock said rod against vertical movement when said ball is in engagement with the cylindrical portion of the peripheral surface of said rod.
 4. In a lifting device, the combination with a cylinder, a piston reciprocable vertically therein, a superstructure carried by said piston for supporting the load to be lifted, and means for effecting reciprocation of said piston in said cylinder, of means for locking the piston in any position to which it is elevated Comprising a reciprocable rod secured to move with said piston, said rod having an arcuate surface around a portion of its perimeter and a plane surface extending in the direction of its axis along another part of its perimeter, a collar through the bore of which said rod is reciprocable, said collar having a groove in its bore whose outside is inclined toward said rod downwardly, a ball clamping member mounted in said groove to roll therein, and means for manually rotating said rod to move said arcuate surface or said plane surface selectively into engagement with said ball.
 5. A lifting device as claimed in claim 4, wherein spring means is connected to said rod automatically to urge said rod to locked position with said arcuate surface in engagement with said ball when said manual rotating means is released. 